This invention relates to incandescent lamps and, more particularly, to an improved filament implementation wherein a plurality of filaments is utilized within the incandescent lamp.
In a single filament incandescent lamp, an incandescent filament is enclosed within a visible light transmitting envelope. During the lamp's use, the filament is exposed to physical, operational and environmental conditions which cause the filament to stress at points or areas along its length. As a result of these points or areas being stressed the filament eventually breaks, the lamp fails and, subsequently, is completely dark.
Disadvantages result from the aforementioned unpredictable filament breakage, and completely dark and failed lamp. A particular situation of interest involves the safety and well-being of people. Representative examples demonstrating the possible consequences of lamp performance limitations due to the foregoing disadvantages include:
A landlord may be held liable to tenants, while they are on the property, if injury or loss results from a fall or an assault caused by insufficient lighting due to a failed lamp; PA1 Late at night, upon returning home, a person discovers that an inside or outside light has failed. This light was supposed to provide basic security by discouraging any would-be burglars, vandals and any other undesirable encounters; PA1 A person in the basement has to negotiate a potentially dangerous trip back up the stairs in darkness because of a failed lamp; PA1 Elderly and/or disabled people, unable to replace a failed lamp, have to risk potential severe consequences moving about in darkness until an aid replaces the lamp; PA1 A failed exit light could prevent people from locating an emergency exit and evacuating the premises. PA1 Warning lights above studio and darkroom doors are inoperative due to failed lamps; PA1 Warning lights on instrument, control or indicator panels that are inoperative, due to a failed lamp, can lead to catastrophic loss.
It will be appreciated that another attribute of the invention that is of particular interest, is contribution to reduction of economic hardship. The foregoing disadvantages of the single filament lamp could also contribute to economic disaster, as demonstrated by the following illustrative examples:
Prior to this invention no incandescent lamp with a self contained reduced-light level filament failure warning has been available.
Prior to this invention no incandescent lamp that can be operated as a single light-level lamp with a self contained reduced-light level filament failure warning, or as a multi-light level lamp has been available.